The discovery of penicillin and the subsequent development of various semi-synthetic penicillins provided doctors with a valuable armamentarium for the treatment of infections due to various pathogenic microorganisms. However, these antibiotics, as well as other new antibiotics, have several deficiencies. Thus, in general, they are active against only a particular group of organisms and, more importantly, their use has resulted in the emergence of resistant strains of pathogens against which the known antibiotics are inactive. The search, therefore, has continued to find new antibiotics to overcome the deficiencies of the known products. In particular, modifications of the penicillin molecule have been sought in an effort to provide new and more active antibiotics. For example, it had been postulated that the introduction of a methyl group in place of the hydrogen .alpha. to the lactam would provide products of enhanced activity and many chemists in this field tried unsuccessfully to produce such penicillins.